The present invention relates to oral compositions for the control of volatile compounds associated with oral malodor.
"Oral composition" means a composition for topical applications to the oral cavity to clean and care for the teeth as well as the oral cavity surfaces. Representatives of such compositions are oral hygiene products and dentifrices such as mouthwashes or rinses, toothpaste, dental gels, tooth powder, chewing gum, lozenges, and similar products. In addition to cleaning teeth to remove dental plaque, the function of oral hygiene preparations is to stop the formation of dental calculus, to prevent dental disorders such as caries, periodontitis and gingivitis, and also to eliminate halitosis.
Dental plaque is a deposit which forms on teeth and consists of inorganic and organic components derived from saliva, food and bacteria which are present in the oral cavity. When plaque undergoes calcification it forms dental calculus, or tartar as it is sometimes called. Dental calculus is largely calcium and orthophosphate arranged in a crystal lattice called hydroxyapatite (HAP).
Oral malodor, or halitosis, is caused by the putrefactive activity of microorganisms on appropriate substrate components of dental plaque, debris adhering to mucous membranes and salivary cellular elements to produce volatile sulfur compounds. These sulfur volatiles primarily consists of hydrogen sulfide (H.sub.2 S), methyl mercaptan (CH.sub.3 SH) and traces of dimethyl sulfide (CH.sub.3).sub.2 S. Volatile sulfur compounds, aromatic amines, ammonia and urea have also been shown to increase in the mouth of patients suffering from periodontal disease, see, for example, J. Periodontal Res., 15, 185-192 (1980), Clin. Chem., 27, 842-845 (1981), Intl. Den. J. 28, 309-319 (1978).
Methods of inhibiting volatile sulfur compounds to reduce the production of mouth odor have included the use of dentifrices containing antimicrobials, such as, chlorhexidine. However, the side effects associated with chlorhexidine, such as a bitter taste and staining of the teeth, tongue, gums and oral mucosa, precludes the use of chlorhexidine in oral compositions.
Copper compounds including copper chlorophyllin, copper gluconate, copper citrate and copper long chain alkyloyl sarcosine have been used to reduce mouth odors. See, for example, U.S. Pat. Nos. 3,044,939; 3,565,933 and 4,112,066 and Nippon Shishyubyo Gakkai Kaishi, 490-498 (1981) for oral compositions containing such compounds. These copper compounds, however, do not fully exert their mouth odor reducing effect when blended in relatively small amounts. As copper is astringent, the amount of these copper compounds required to assure their effect in reducing mouth odor makes such oral compositions unpleasant in taste.
An oral composition containing copper gluconate, a fluorine compound, and an alkali metal salt of an alkyl sulfate having 8 to 18 carbon atoms is reported in published European Patent Application 0321180. It was reported that these components act in a synergistic manner so that mouth odor suppression is accomplished when each ingredient is contained in a low concentration.
While the use of copper compounds in oral compositions for controlling mouth malodor is known, none of the references provide a means by which the copper can be retained in the oral cavity to control mouth odor over a period of time. In addition, many copper compounds are unstable at biological pH (about 7.0) resulting in undesirable cloudiness and precipitation of insoluble by-products.
It is therefore desirable when using copper in an oral composition to control mouth malodor, to have an oral composition in which the copper compound is effective at a relatively low concentration, can be maintained in the oral cavity over a prolonged period of time, and remains soluble when used in liquid compositions. It would also be desirable to prepare an oral composition capable of controlling mouth malodor in addition to the prevention of plaque and calculus formation.